The invention relates to detectors and, more particularly, to an apparatus and method for pile-up correction in a photon-counting detector for medical imaging and similar applications.
X-ray computed tomography imaging, also referred to as Computed Tomography (CT) or Computed Axial Tomography (CAT), employs computer-processed X-ray projections to generate images of the interior of an object of interest. These systems generally successively emit and detect photons in the X-ray energy range, directed toward an object, so as to generate a plurality of consecutive-projection data of the object's contents. The projection data may then be used to generate a three-dimensional image of the inside of the object. The three-dimensional image may be used for diagnostic and therapeutic purposes in various medical disciplines, but may also be used in a wide variety of other contexts, such as baggage inspection and industrial part inspection.
CT photon-counting detection systems, and certain X-ray detection systems in general, may seek to improve image quality by counting a number of photons that are received at a radiation detector. Such photon-counting detectors may, for example, reduce or eliminate electronic noise and/or provide improved energy-resolving capabilities. In many clinical applications, however, the photon flux generated by the X-ray tube of diagnostic CT is much higher than what currently available photon-counting detectors can accommodate. As a result, a photon-counting detector may experience a “pile-up” condition where X-ray photons arrive at the detector at such a rate that it may be difficult to determine which X-ray detection event is associated with each particular photon. Pile up causes error in both the estimation of the number and energy of the detected photons; these errors may cause the quality of a generated image to be degraded.
Therefore, it would be desirable to design an apparatus and method to provide an accurate estimate of both the count and energy of detected X-ray photons with a photon-counting detector in a practical manner.